1. Field
The disclosure relates to a method, system, and article of manufacture for the execution of point-in-time copy operations in continuous mirroring environments.
2. Background
In certain storage environments, asynchronous, continuous mirroring solutions may operate by copying updated data from a source storage subsystem to a target storage subsystem in a time-sequenced order, where the time-sequenced order is based on the time the data was updated by an application program. In such continuous mirroring solutions, source storage volumes, also referred to as continuous copy source volumes, are copied via continuous copy operations to target storage volumes, also referred to as continuous copy target volumes.
Point-in-time copy operations may attempt to copy source storage volumes, also referred to as a point-in-time source volumes, to target storage volumes, also referred to as point-in-time target volumes. In point-in-time copy operations, the point-in-time target volumes are updated with the data stored at the point-time-time source volumes at a single point-in-time. Furthermore, in point-in-time copy operations instantaneous or substantially instantaneous updates are made to the point-in-time target volumes with data from the point-in-time source volumes.
In certain situations, point-in-time copy operations have to be performed while continuous copy operations are being performed within a storage environment. Large scale point-in-time copies made onto a continuous mirror source volume (i.e., the continuous mirror source volume is the target volume for a point-in-time copy operation) may cause problems in certain storage environments because all the data included in the domain of the point-in-time copy may be logically updated instantaneously, and data consistency may be lost.
In certain existing implementations of continuous copy solutions, a record set may be created for each of the tracks updated by the point-in-time copy, wherein all of these record sets may have the same timestamp and may have to be physically copied to the continuous copy target volumes at the same time in order to maintain data consistency. Consistency can also be maintained by consecutively updating the continuous copy target volumes with the continuous copy source (i.e., point-in-time target) tracks, but this may prevent other application updates from being applied to the continuous copy target volumes until the entire range of the point-in-time copy is mirrored.
In certain customer environments where an entire data center is mirrored using continuous copy, in certain solutions the available choices for the customer are to disable mirroring while point-in-time operations are processed, or to not use point-in-time operations.